To keep the poncho from leaking in the center, pull the drawstings of the hood until the hood is sealed up. I usually place the hood on the outside, preventing any unwanted moisture from pooling up.

When in the field, I carried two ponchos, one with the poncho liner tied in place, and the other as a ground cloth/shelter half. When used with a quality ground pad of some sort, (I used two, the standard GI issue foam made a great ground cloth, and a civilian self inflating pad) the system works well in temperatures down to the 20's. It's also light, modular, and versitile.